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Pollution Prevention
Ask the Expert Question-and-Answer Archive

by George CushnieSeptember, 2009

Ion Resins

Q.I am considering setting up a facility to regenerate ion exchange resins to serve the metal finishing industry. I am trying to better understand who uses these resins, for what, who currently serves that need, how much resin they use, and what the cost is.

Can you tell me who I might speak to about this?

A. The concept you describe is referred to as centralized waste treatment (CWT). I co-authored a book on this subject in 1985 (there are used copies around for under $10...seach for ISBN 0815510381). This concept was highly successful in Europe, where it started during the 1970s (I dont know the current status of it there). In the U.S., I know of one company (U.S. Filter) that successfully did what you are describing. They were (and maybe still are, but under a different name) located in Minneapolis, MN. There were other smaller attempts at it, but I dont remember where they were located.

CWT competes with on-site treatment, which can entail use of ion exchange, but more often involves precipitation of metals using caustic. Startup of a CWT facility would be fairly expensive, certainly into the millions of dollars. The difficulty, as I see it, would be convincing plating companies (and industries with similar wastes) to give up their on-site treatment in favor of CWT. This decision would most likely boil down to price.

Q2. Thank you for your thoughtful response. You have already responded beyond the call of duty but if it is not an imposition, I would also be curious if you thought there were other services we could provide this market, such as treating contaminated water?

A2. One possibility is to treat/recycle used process solution on-site so that the solutions could be reused. Two solutions that come to mind are hard chrome plating baths and alkaline cleaners. Conventional hard chrome baths can be rejuvenated with ion exchange (removes tramp metals) and alkaline cleaners can be rejuvenated using ceramic microfiltration (removes oils and suspended solids). Plating shops could buy these technologies, but they are usually not cost effective for a single shop to own them. Plus, they require some expertise to operate and they generate residual wastes that need to be hauled off-site for treatment/disposal.

I could picture a recycling company that has these technologies mounted on a truck that backs up to the back of a shop, treats the process solutions for a day and leaves. The benefit to the shop is that they dont have to dispose of and remake the entire bath (very costly).

With a more complicated scenario, I could see a chemical maintenance company that owns the solutions that are in the tanks rather than the plating shop. The solution maintenance company is responsible for testing the solutions, making needed chemical additions, and treating them when necessary. I believe this kind of approach is used in the machining business with cutting oils.